In wireless communication systems, for example, cellular communication systems such as Wideband Code Division Multiple Access (WCDMA) and/or CDMA, a receiver may be based on a RAKE receiver architecture. The RAKE receiver may be used for an additive white Gaussian noise (AWGN) channel. For example, the CDMA/WCDMA cellular communication system may utilize Common Pilot Channels (CPICH) to broadcast pilot signals from base stations of the cellular system. The broadcast of multiple pilot signals may cause interference at the RAKE receiver. A Pilot Interference cancellation (IC) technique may be used to cancel the pilot signal interference. The Pilot IC technique may estimate and cancel at the RAKE receiver the interference effect of the broadcast.
Another technique for canceling interference is linear interference suppression. For example, in a linear interference suppression technique, a linear transformation (or a filter) may be applied to the input signal in order to reduce the interference seen by the receiver. One type of linear interference suppression technique may include linear Minimum Mean Squared Error (MMSE) processing, where a linear transformation/filter may be applied to the input signal to produce an output estimate of the desired symbol, thereby minimizing the mean square error (MSE).
Other linear interference suppression techniques, such as, for example a Decorrelating Multiuser detector and a zero-forcing equalizer are known in the art. In these two examples, the linear transformation may be optimized to completely eliminate the co-channel interference, without taking the noise level into account; thus, these receivers may suffer from noise enhancement. In contrast, in linear MMSE processing the applied linear transformtion may be dependent on the noise level.
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